Electric discharge device



1966 K. J. GERMESHAUSEN ETAL 3,

ELECTRIC DISCHARGE DEVICE Filed Aug. 22, 1962 IS A l3 ES l5\ T 20 C L\ \w DIRECTION OF MAGNETIC FORCE F|G.2

4 u L r KENNETH J.GERMESHAUSEN C SEYMOUR GOLDBERG 20 INVENTORS DIRECTION OF MAGNETIC FORCE MAX/( 4 ATTORNEYS United States Patent 3,283,199 ELECTRIC DISCHARGE DEVICE Kenneth J. Germeshausen, Weston, and Seymour Goldberg, Lexington, Masa, assignors to Edgerton Germeshausen & Grier, line, Boston, Mass, a corporation of Massachusetts Filed Aug. 22, 1952, Ser. No. 218,596 11 Claims. (Cl. 313-306) This invention relates to electric discharge devices, and more particularly to spark gaps.

Spark gaps have been well known in the art for a long peroid of time. They are very useful in many different applications, including, but not limited to light sources, switches for both single and repetitive operation, and protective devices for costly equipment such as crowbar applications.

Many factors affect the useful life of spark gaps. Probably the most important factor in shortening the life of a spark gap is elctrode erosion and the deleterious effects caused thereby. Our investigations have shown us that, under similar operating conditions, the rate of electrode erosion is substantially the same in spark gaps regardless of the medium (ionizable air, gas, or vacuum) between the discharge electrodes.

In all spark gaps, whether they are triggered or untriggered, a cathode spot of an intense temperature is formed on the negative electrode. It is from this cathode spot that the arc discharge originates and moves through the path of least impedance to the opposite or positive electrode. A similar region of intense temperature is also formed at the positive terminus of the arc. The greatest electrode erosion takes place at these regions. The rate at which the electrodes erode is a factor of the amplitude and time duration of the current pulse passed during discharge and the material from which the electrode is constructed. Great improvements have been made in the materials from which electrodes are constructed with a resulting decrease in electrode erosion. Even with these improvements, the erosion rate is still sutficiently great to considerably shorten the life of spark gaps. It is known that the rate of electrode erosion with respect to the time duration of the discharge arc is not constant, but rather it increases as the time duration increases. For example, with the same rate of current flow, the total erosion which takes place due to a two-millisecond pulse is more than double the erosion caused by a one-millisecond pulse.

When the discharge are is originated, and the erosion takes place, particles of the elctrode material are sputtered from the electrodes to surrounding areas within the tube. Depostion of eroded electrode material on an insulator which separates the two principal electrodes, as is quite often found in many of the gas-filled spark gaps, can cause a change in the operating voltages of the spark gap. When a sufiicient quantity of the eroded material is so deposited upon this insulator, discharge or breakdown may be produced at a lower potential than the normal voltage difference which the device is designed to hold off. In fact, the spark gap may be rendered useless because of this condition.

If the eroded material is deposited upon the insulator separating the trigger electrode from one of the principal electrodes, the trigger may become shorted to that electrode, thereby causing misfirings when the tube is triggered. The further disadvantage of electrode erosion is that it physically changes the gap spacing between the principal electrodes thereby lowering the static breakdown voltage across these two electrodes.

It is, therefore, an object of this invention to provide a spark gap which is not subject to the aforementioned disadvantages.

Biddlg Patented Nov. l, 1966 Another object is to provide a spark gap in which electrode erosion is substantially reduced and the life of the device is thereby substantially extended.

A further object of this invention is to provide a spark gap in which electrode erosion is spread out over a wide area of the electrode surface, and the total erosion is considerably reduced.

Still another object is to provide a new and novel spark gap.

Other and further objects of this invention are pointed out hereinafter in the specifications and in the appended claims. In summary, this invention consists of a triggered spark gap having elongated electrodes with electrical connections thereto so positioned that during discharge, the current flow through the electrodes produces an unbalanced magnetic force which acts upon the arc discharge causing it to move along the electrode surfaces. Modifications and preferred constructional details are set forth hereinafter.

Our invention will be better understood by referring to the following description taken in connection with the attached drawings:

FIGURE 1 of which is a schematic drawing of a spark gap inserted for explanatory purposes;

FIGURE 2 is a cross-sectional view of a spark gap embodying the principles of our invention;

FIGURE 3 is a modification of the spark gap shown in FIGURE 2; and

FIGURE 4 is another embodiment of the invention.

Referring first to FIGURE 1, a spark gap is shown having symmetrical current connections to each of the principal electrodes 10 and 20. The arrows A and B indicate dual connections to the ends of electrode 10 from one side of a high-voltage source (not shown) such as a capacitor bank charged to a high potential. The voltage is insuflicient to cause a discharge between the electrodes 10 and 20 in the absence of a triggering impulse. Arrows C and D represent a pair of connections from electrode 20 to the opposite side of said high-voltage source. Using the conventional concept of current flow, that is, from a positive potential to a negative potential, in the direction opposite to the electron flow, the arrows A, B, C, and D indicate the direction of current flow when the spark gap is actuated and a discharge takes place between the principal electrodes 10 and Ztl. A discharge is initiated by the application of a trigger pulse to the trigger electrode 11 which is disposed in electrode 10, but separated therefrom by insulator 12. Under the influence of the trigger pulse, the impedance between the principal electrodes 10 and 2% is reduced, thereby causing the highvoltage connected thereacross to discharge. The mechanics of the impedance reduction depend upon the type of spark gap, that is, the medium between the principal electrodes which may be air, an ionizable gas, or a vacuum. Regardless of the nature of this medium, the impedance is reduced and the main discharge takes place.

When the discharge takes place, it originates at a cathode spot of intense temperature on electrode 20 which point is arbitrarily indicated by reference designator 16. The discharge then rapidly moves through the medium in the gap spacing to a point on electrode 10 indicated by designator 17 which also rises to an intense temperature. The are discharge is shown by the line 15 in the drawing. Because of the arrangement of the connectors A, B, C, and D, the current flow is symmetrical. It flows from the source of high voltage potential through connectors A and B at opposite ends of electrode 10 and thence to point 17 on electrode 10. From point 17 it passes through the discharge are 15 to point 16 on electrode 20 where it divides and one portion flows through electrode ZIP to output connector C while the other portion flows through electrode 20 to output connector D. From output connectors C and D the current flow returns to the opposite side of the high-voltage source. The current flowing through electrodes and 20 produces a magnetic force which is mutually perpendicular to the flow of the current in the magnetic field created thereby. Thus, the flow of current from input connector A through electrode 10 to point 17 creates a magnetic field about electrode 10, and a magnetic force which acts upon the discharge are tending to push it to the right. At the same time, a substantially equal current flows through connector B along electrode 10 to point 17 which also creates a magnetic field about electrode 10 opposite to that produced by the current entering at point A. The magnetic force produced by the current from connector B is equal and opposite to that produced by the current from connector A and therefore, the total force exerted by these two magnetic forces acts to compress the discharge are and to anchor it in its originating position, thereby preventing any movement. Similarly, each of the output currents passing from point 16 through electrode to connectors C and D produces a magnetic force that acts upon discharge arc 15 causing compression thereof and preventing any movement of the arc. The net effect of the magnetic forces produced by the current flow in the two principal electrodes 10 and 20 is to compress the discharge are 15 and since the magnetic forces are balanced, there is no movement of the discharge are.

If input connector B and output connector C were removed, the current flow during discharge would pass from connector A along electrode 10 to point 17 through the discharge 15 to point 16 and thence through electrode 20 to output connector D. In this case, the current flow through electrode 10 would produce a magnetic field as described above and a magnetic force tending to push the discharge are 15 to the right, while the current flow in electrode 20 creates a magnetic force which acts to push the discharge are 15 to the left. The resultant force therefore, again, acts to compress the discharge and and anchor it in its original position.

If, however, input connector B and output connector D were removed from the circuit leaving the current to flow from connector A through electrode 10 to point 17 and then through the discharge arc 15 to point 16 and thence along electrode 20 to output connector C, the magnetic forces produced by the current flow in the two electrodes would produce magnetic forces on the discharge are 15 and cause it to move to the right along electrodes 10 and 20. The greater the distance that the are moved, the greater would be the magnetic force acting upon it due to the increased current path through electrodes 10 and 20, thereby producing even more rapid motion along electrodes 10 and 20.

FIGURE 2 discloses a spark gap constructed according to the principles of our invention. One of the principal electrodes 20 is shown as a cylindrical rod having one end thereof rounded. The other principal electrode 10 forms a portion of the envelope wall and is concentric with electrode 20. Electrode 10 is a hollow cylinder having one end closed and has side wall surfaces disposed substantially equi-distant from the sides of electrode 20. The other end of electrode 10 has an outwardly extending flange A which serves as the electrical connection to electrode 10. Other configurations may be also used as long as the distance between the two electrodes remains substantially constant and elongated to permit the discharge are to move away from the point at which it originates. An insulating material 18, such as ceramic or the like, forms another portion of the envelope wall. Insulator 18 is sealed to one side of flange A by any well known method of bonding metal to ceramic and the like such as that shown in US. Letters Patent No. 2,842,699 issued on July 8, 1958, to the applicants herein, or US. Letters Patent No. 3,031,737, issued on May 1, 1962, to Fred M. Conley. An insulating ring 13 is disposed on the opposite side of flange A and sealed thereto for greater structural strength. An end piece 19 may be used to complete the envelope construction. A trigger electrode 11 is disposed within the envelope adjacent to principal electrode 10. Trigger electrode 11 is connected to a source of triggering impulses (not shown) by connector 14. The principal electrodes 10 and 20 are connected across a high-voltage potential (not shown) by means of connectors A and C, respectively. It should be noted that the trigger electrode 11 is disposed adjacent to principal electrode 10 which is connected to the high-voltage potential, and that connectors A and C are located at corresponding ends of electrodes 10 and 20. In this way, the discharge forms near the end of electrode 10 and the direction of current flow during discharge produces a magnetic force which causes the arc to move toward the other end of electrode 10. This spark gap may be used with an ionizable gas, air, or a vacuum between the principal electrodes. As pointed out above, the gap spacing between the principal electrodes and the operating potentials and trigger potential will vary depending upon the medium disposed between the principal electrodes 10 and 20. For the purposes of this discussion, we will consider the spark gap of FIGURE 2 to be a vacuum gap having a vacuum in excess of 10- millimeters of mercury. It is a characteristic of vacuum spark gaps that to cause a discharge between the principal electrodes a relatively high voltage trigger pulse is required. One means for reducing to some extent the voltage required to trigger such a spark gap is to dispose the trigger electrode very close to, but out of contact with insulator 18. By doing this, a very intense electric field is created between the trigger electrode 11 and the insulator 18 which facilitates triggering within the device. When a high-voltage trigger pulse is applied to trigger electrode 11, an intense electric field is created at the end of the trigger electrode thereby causing an arc discharge from electrode 10 to trigger electrode 11. By making the trigger pulse of very short duration, only a very small amount of erosion takes place at electrode 10 due to the initiation of the triggering arc. The trigger arc consists of ionized particles from electrode 10. The high-voltage connected across electrodes 10 and 20 creates an intense electric field therebetween and the ionized particles in the trigger discharge are are accelerated by this intense electric field and strike electrode 20 with sufficient energy to liberate gas and metal vapor which, in turn, are readily ionized to form a low impedance discharge path between electrodes 10 and 20. The potential from the high-voltage source thereby discharges between electrodes 10 and 20 producing discharge are 15. Due to the arrangement of the connectors A and C, current is caused to flow from the source of highvoltage through connector A to electrode 10, passing to the right along electrode 10 to the discharge are 15 and thence through electrode 20 to output connector C and back to the high-voltage source. The flow of current along electrode 10 from connector A to the discharge arc 15 creates a magnetic field about electrode 10 in this region and this magnetic field produces a magnetic force mutually perpendicular to both the flow of current and to the magnetic field itself thereby exerting an unbalanced force upon arc discharge 15 tending to move it to the right along electrodes 10 and 20. The current flow along electrode 20 also creates a magnetic field about the electrode which field in turn creates a magnetic force which is additive to the force created by the current flow in electrode 10. Both magnetic forces tend to exert an unbalanced force upon the arc discharge forcing it in a direction to the right as shown by the arrow in the figure. The arc discharge 15 will move very rapidly to the right under the influence of this unbalanced force and the further the discharge moves, the greater the unbalanced force acting upon it, and the greater the speed of movement will be. The are discharge will extinguish itself when the voltage potential is reduced to a level that will not sustain the arc.

By moving the arc along the path between the principal electrodes and 20, erosion of electrodes 10 and 2% is considerably reduced, particularly at the points where the discharge are originates. If the are discharge 15 has a longer time duration than the transit time of the are along the principal electrodes, the greatest erosion takes place at the end of electrode at the point where the arc is extinguished. Itshould be observed from this configuration that erosion at the end of electrode 20 is much less detrimental to the life of the device because the gap spacing is not altered in the region Where the arc originates. Furthermore, the eroded material sputtered from the end of electrode 20 will almost entirely be deposited upon electrodes 10 and 20 where it will do no injury to the device. Only an extremely small quantity of eroded material could possibly be deposited on insulator 18 in the region between trigger electrode 11 and principal electrode 10, where it could tend to cause a short circuit in the triggering of the device, thereby producing premature failure. It should also be observed that the arc discharge is considerably removed from the rest of the insulator 18 between the principal electrodes 10 and 20 so that there is practically no possibility of eroded materials being deposited upon insulator 13 to lower the static breakdown voltage of the device and consequently shortening its life.

Although the trigger pulse fed to trigger electrode 11 is of short duration, some erosion takes place as a result of the trigger arc. The erosion is located at a point on electrode 10 adjacent to trigger electrode 11. After the gap has been triggered, a large number of times, the erosion on electrode 10 can effect the triggering potentials and more particularly cause an increase in the size of the trigger potential necessary to create the trigger arc. Another problem which may arise due to the triggering arc is erosion of the ceramic insulator 1% in the vicinity of the trigger electrode 11 due to the trigger arc and the intense electric field created between trigger electrode 11 and insulator 18. The result of erosion at this point is that the distance separating the trigger electrode 11 from insulator 18 is increased, thereby decreasing the intensity of the electric field produced by the triggering pulse.

The spark gap shown in FIGURE 3 is a modification of the spark gap shown in FIGURE 2. The trigger electrode is no longer a single electrode but is a circular ring 11 having the same inner diameter as electrode 19 and spaced therefrom. By using a ring-type trigger electrode 11, erosion of either electrode 10 or insulator 18 does not affect the trigger potential necessary to initiate the arc discharge because there is a large trigger surface available to produce the intense electric field and cause the triggering arc. When any one point of electrode 16 and insulator 18 becomes eroded, there is a large number of other points available to initiate the arc. It is not essential that a triggering ring, as shown in FIGURE 3 be used. A plurality of trigger electrodes similar to that shown in FIGURE 2, and disposed about eletcrode 2d, would adequately increase the life of the spark gap. Another improvement which has been incorporated into the design shown in FIGURE 3 are the solenoids 21 disposed on the outer surface of, and insulated from, electrode It). By connecting these solenoids 21 to a source of potential (not shown), a magnetic field is created as shown by the dotted lines 22 in the figure. The magnetic field 2.2 creates a magnetic force which will act upon the main discharge are 15 tending to cause the arc to rotate about electrode 20. The two forces, one caused by current flow and the other by the solenoids 21, act at right angles to each other with a resultant force that 6 causes the arc to move in a helical path about electrode 20.

It can thus be seen that in the device of FIGURE 3, the discharge are may be initiated at any point around electrode 20 in the vicinity of the trigger electrode 11 and thence it moves in a heleical path about electrode 269. In this way erosion is reduced to a minimum and the life of the device is correspondingly increased.

Another embodiment of our invention is shown in FIGURE 4. The principal electrodes 10 and 20 are substantially parallel to each other and may be cylindrically or rectangularly shaped or of any other elongated shape. The trigger electrode 11 is disposed between electrodes 10 and 20, closer to the end at which connectors A and C are located to couple electrodes lit and 20 across a source of high-voltage (not shown). Although this embodiment may be sealed in an evacuated envelope or an envelope with a filling of an ionizable gas, we prefer to use it in an air medium.

By connecting the high-voltage to electrodes 1t and 24) at the same ends of these electrodes, and by disposing the trigger electrode 11 closer to this end, the discharge are is caused to form near this end when the device is triggered, and the magnetic forces, created by the current flow from input connector A through electrode 10, discharge arc 15, and electrode 20 to output connector C, cause the arc to move along the substantially parallel electrodes 10 and 20, away from connectors A and C in the direction shown by the arrow in the figure. The length of electrodes 10 and 20 may be sufiiciently long that the arc will be extinguished before it reaches the end of the electrodes. If this is not the case, the arc will maintain itself at this end until the discharge potential decreases to a point at which the arc can no longer be maintained. When the are so maintains itself at the end, the greatest electrode erosion takes place there, but, as we have pointed out above, erosion at that end is not a serious problem because it does not effect the triggering action nor the creation of discharge are 15 in response to the triggering impulse.

It is obvious that further modifications will occur to those skilled in this art and all such are considered to fall within the spirit and scope of our invention.

We claim:

1. An electric discharge device comprising an elongated rod-shaped first electrode, a hollow elongated second electrode having a closed end and enclosing a portion of said first electrode and being disposed in concentric relation thereto and in spaced apart relation therefrom and having a fiange portion at its open end, a hollow cylindrical insulating member secured to said flange portion of said second electrode and in concentric relation to and spaced apart from said first electrode, said second electrode and said insulating member forming the envelope wall of said discharge device, a trigger electrode mounted adjacent said flange portion of said second electrode and being disposed in the space separating said first electrode from said insulating member, means for connecting said first and second electrodes across source of high voltage potential in such a manner that said connecting means for said first electrode being disposed at an end opposite to the end enclosed by the said second electrode and said connecting means for said second electrode being made to said flange portion thereof so that during a discharge, current flows in opposite directions through adjacent sections of said first and second electrodes creating thereby an unbalanced magnetic field therebetween acting upon said discharge to cause it to move along the surfaces of said first and second electrodes and toward said closed end thereof, and means for applying a trigger impulse to said trigger electrode.

2. An electric discharge device comprising an elongated rod-shaped first electrode, a hollow elongated second electrode having a closed end and enclosing a portion of said first electrode and being disposed in concentric relation thereto and in spaced apart relation therefrom and having a flange portion at its open end, a hollow cylindrical insulating member secured to said flange portion of said second electrode and in concentric relation to and spaced apart from said first electrode, said second electrode and said insulating member forming the envelope wall of said discharge device, an electromagnetic field producing source disposed on the exterior surface of said second electrode adjacent said flange portion thereof, a trigger electrode mounted adjacent said flange portion of said second electrode and being disposed in the space separating said first electrode from said insulating member, means for connecting said first and second electrodes across a source of high voltage potential in such a manner that said connecting means for said first electrode being disposed at an end opposite to the end enclosed by the said second electrode and said connecting means for said second electrode being made to said flange portion thereof so that during a discharge, current flows in opposite directions through adjacent sections of said first and second electrodes creating thereby an unbalanced magnetic field therebetween, said electromagnetic field producing source being provided for creating an electromagnetic force which, in conjunction with said unbalanced magnetic field, acts upon said discharge to cause it to rotate in a helical path about said first electrode and in a direction toward said closed end of said second electrode, and means for applying a trigger impulse to said trigger electrode.

3. An electric discharge device comprising an elongated rod-shaped first electrode, a hollow elongated second electrode having a closed end and enclosing a portion of said first electrode and being disposed in concentric relation thereto and in spaced apart relation therefrom and having a flange portion at its open end, a hollow cylindrical insulating member secured to said flange portion of said second electrode and in concentric relation to and spaced apart from said first electrode, said second electrode and said insulating member forming the envelope wall of said discharge device, a plurality of trigger electrodes mounted adjacent said flange portion of said second electrode in spaced apart relation to each other and lying in a plane, means for connecting said first and second electrodes across a source of high voltage potential in such a manner that said connecting means for said first electrode being disposed at an end opposite to the end thereof enclosed by the said second electrode and said connecting means for said second electrode being made to said flange portion thereof so that during a discharge, current flows in opposite directions through adjacent sections of said first and second electrodes creating thereby an unbalanced magnetic field therebetween acting upon said discharge to cause it to move along the surfaces of said first and second electrodes and toward said closed end thereof, and means for applying a trigger impulse to said trigger electrode.

4. An electric discharge device comprising an elongated rod-shaped first electrode, a hollow elongated second electrode having a closed end and enclosing a portion of said first electrode and being disposed in concentric relation thereto and in spaced apart relation therefrom and having a flange portion at its open end, a hollow cylindrical insulating member secured to said flange portion of said second electrode and in concentric relation to and spaced apart from said first electrode, said second electrode and said insulating member forming the envelope wall of said discharge device, a trigger electrode formed as an annular ring and being disposed adjacent said flange portion of said second electrode and encircling said first electrode and radially occupying the space separating said first electrode from said insulating member, means for connecting said first and second electrodes across a source of high voltage potential in such a manner that said connecting means for said first electrode being disposed at an end opposite to the end thereof enclosed by the said second electrode and said connecting means for said second electrode being made to said flange portion thereof so that during a discharge, current flows in opposite directions through adjacent sections of said first and second electrodes creating thereby an unbalanced magnetic field therebetween acting upon said discharge to cause it to move along the surfaces of said first and second electrodes and toward said closed end thereof, and means for applying a trigger impulse to said trigger electrode.

5. An electric discharge device comprising an elongated rod-shaped first electrode, a hollow elongated second electrode having a closed end and enclosing a portion of said first electrode and being disposed in concentric relation thereto and in spaced apart relation therefrom and having a flange portion at its open end, a hollow cylindrical insulating member secured to said flange portion of said second electrode and in concentric relation to and spaced apart from said first electrode, said second electrode and said insulating member forming the envelope wall of said discharge device, an electromagnetic field producing source disposed on the exterior surface of Said second electrode adjacent said flange portion thereof, a plurality of trigger electrodes mounted adjacent said flange portion of said second electrode in spaced apart relation to each other and lying in a plane, means for connecting said first and second electrodes across a source of high voltage potential in such a manner that said connecting means for said first electrode being disposed at an end opposite to the end thereof enclosed by the said second electrode and said connecting means for said second electrode being made to said flange portion thereof so that during a discharge, current flows in opposite directions through adjacent sections of said first and second electrodes creating thereby an unbalanced magnetic field therebetween, said electromagnetic field producing source being provided for creating an electromagnetic force which, in conjunction with said unbalanced magnetic field, acts upon said discharge to cause it to rotate in a helical path about said first electrode and in a direction toward said closed end of said second electrode, and means for applying a trigger impulse to said trigger electrode.

6. An electric discharge device comprising an elongated rod-shaped first electrode, a hollow elongated second electrode having a closed end and enclosing a portion of said first electrode and being disposed in concentric relation thereto and in spaced apart relation therefrom and having a flange portion at its open end, a hollow cylindrical insulating member secured to said flange portion of said second electrode and in concentric relation to and spaced apart from said first electrode, said second electrode and said insulating member forming the envelope wall of said discharge device, an electromagnetic field producing source disposed on the exterior surface of said second electrode adjacent said flange portion thereof, a trigger electrode formed as an annular ring and being disposed adjacent said flange portion of said second electrode and encircling said first electrode and radially occupying the space separating said first electrode from said insulating member, means for connecting said first and second electrodes across a source of high voltage potential in such a manner that said connecting means for said first electrode being disposed at an end opposite to the end thereof enclosed by the said second electrode and said connecting means for said second electrode being made to said flange portion thereof so that during a discharge, current flows in opposite directions through adjacent sections of said first and second electrodes creating thereby an unbalanced magnetic field therebetween, said electromagnetic field producing source being provided for creating an electromagnetic force which, in conjunction with said unbalanced magnetic field, acts upon said discharge to cause it to rotate in a helical path about said first electrode and in a direction towards said closed end of said second electrode, and means for applying a trigger impulse to said trigger electrode.

7. An electric discharge device comprising an elongated first electrode of substantially cylindrical configuration, a. hollow elongated second electrode enclosing at least a portion and one end of the first electrode and disposed a uniform distance therefrom, a trigger electrode disposed adjacent the second electrode remote from the end thereof enclosing said end of the first electrode, means for connecting the first and second electrodes across a source of high-voltage potential, said connecting means for the second electrode being disposed remote from said enclosing end, said connnecting means for the first electrode being disposed so that during a discharge, current flows in opposite directions through adjacent sections of the first and second electrodes creating thereby an unbalanced magnetic field therebetween, means for applying a triggering impulse to the trigger electrode for rendering the device effective, and an electromagnetic field producing source disposed on the exterior surface of the second electrode creating an electromagnetic force acting upon said discharge when the device is effective to cause the discharge to rotate about said first electrode.

8. An electric discharge device comprising an elongated first electrode of substantially cylindrical configuration, a hollow elongated second electrode enclosing at least a portion and one end of the first electrode and disposed a uniform distance therefrom, a plurality of trigger elec trodes disposed adjacent the second electrode remote from the end thereof enclosing said end of the first electrode and spaced from each other and lying in a plane, means for connecting the first and mcond electrodes across a source of high-voltage potential, said connecting means for the second electrode being disposed remote from said enclosing end, said connecting means for the first electrode being disposed so that during a discharge, current flows in opposite directions through adjacent sections of the first and second electrodes creating thereby an unbalanced magnetic field therebetween, and means for applying a triggering impulse to the trigger electrode for rendering the device effective.

9. An electric discharge device as claimed in claim 8 and further comprising:

an electromagnetic field producing source disposed on the exterior surface of the second electrode creating an electromagnetic force acting upon said discharge when the device is effective to cause the discharge to rotate about the first electrode.

10. An electric discharge device comprising an elongated first electrode of substantially cylindrical configuration, a hollow elongated second electrode enclosing at least a portion and one end of the first electrode and disposed a uniform distance therefrom, an annular trigger electrode disposed adjacent the second electrode remote from the end thereof enclosing said end of the first electrode and encircling the first electrode, means for connecting the first and second electrodes across a source of high-voltage potential, said connecting means for the second electrode being disposed remote from said enclosing end, said connnecting means for the first electrode being disposed so that during a dis-charge, current flows in opposite directions through adjacent sections of the first and second electrodes creating thereby an unbalanced magnetic field therebetween, and means for applying a triggering impulse to the trigger electrode for rendering the device effective.

11. An electric discharge device as claimed in claim 10 and further comprising:

an electromagnetic field producing source disposed on the exterior surface of the second electrode creating an electromagnetic force acting upon said discharge when the device is effective to cause the discharge to rotate about the first electrode.

References Cited by the Examiner UNITED STATES PATENTS 1,603,279 10/1926 Gray 313-214 2,063,580 12/1936 Braselton 313-214 2,411,241 11/1946 Arnott 313-214 2,422,324 6/1947 Watrous 313-214 2,507,696 5/1950 Depp 313-214 2,564,040 8/1951 Vance 313-198 2,870,365 1/1959 Frouws 313-208 2,913,626 11/1959 Bislin 313-231 2,941,099 6/ 1960 ,Pi-card 313-231 3,067,353 12/1962 Frouws 313-198 JOHN W. HUCKERT, Primary Examiner.

J. D. KALLAM, Assistant Examiner. 

1. AN ELECTRIC DISCHARGE DEVICE COMPRISING AN ELONGATED ROD-SHAPED FIRST ELECTRODE, A HOLLOW ELONGATED SECOND ELECTRODE HAVING A CLOSED END AND ENCLOSING A PORTION OF SAID FIRST ELECTRODE AND BEING DISPOSED IN CONCENTRIC RELATION THERETO AND IN SPACED APART RELATION THEREFROM AND HAVING A FLANGE PORTION AT ITS OPEN END, A HOLLOW CYLINDRICAL INSULATING MEMBER SECURED TO SAID FLANGE PORTION OF SAID SECOND ELECTRODE AND IN CONCENTRIC RELATION TO AND SPACED APART FROM SAID FIRST ELECTRODE, SAID SECOND ELECTRODE AND SAID INSULATING MEMBER FORMING THE ENVELOPE WALL OF SAID DISCHARGE DEVICE, A TRIGGER ELECTRODE MOUNTED ADJACENT SAID FLANGE PORTION OF SAID SECOND ELECTRODE AND BEING DISPOSED IN THE SPACE SEPARATING SAID FIRST ELECTRODE FROM SAID INSULATING MEMBER, MEANS FOR CONNECTING SAID FIRST AND SECOND ELECTRODES ACROSS A SOURCE OF HIGH VOLTAGE POTENTIAL IN SUCH A MANNER THAT SAID CONNECTING MEANS FOR SAID FIRST ELECTRODE BEING DISPOSED AT AN END OPPOSITE TO THE END ENCLOSED BY THE SAID SECOND ELECTRODE AND SAID CONNECTING MEANS FOR SAID SECOND ELECTRODE BEING MADE TO SAID FLANGE PORTION THEREOF SO THAT DURING A DISCHARGE, CURRENT FLOWS IN OPPOSITE DIRECTIONS THROUGH ADJACENT SECTIONS OF SAID FIRST AND SECOND ELECTRODES CREATING THEREBY AN UNBALANCED MAGNETIC FIELD THEREBETWEEN ACTING UPON SAID DISCHARGE TO CAUST IT TO MOVE ALONG THE SURFACES OF SAID FIRST AND SECOND ELECTRODES AND TOWARD SAID CLOSED END THEREOF, AND MEANS FOR APPLYING A TRIGGER IMPULSE TO SAID TRIGGER ELECTRODE. 